With the rapid development of semiconductor manufacturing technologies, semiconductor devices are developed toward the direction of higher component densities and integration degrees. To increase the integration degree of semiconductor devices, the density of transistors is continuously increasing while the space among transistors is decreasing.
When semiconductor devices are developed toward higher integration degrees, the problem of decreased channel carrier mobility can occur. To increase the channel carrier mobility of transistors, a technology based on strained silicon has been introduced, in which a layer of crystal with different lattice constants from the Si substrate is epitaxially grown in the drain and source regions of transistors. Further, to electrically connect the drain and source regions with external circuits, the fabrication method of semiconductor structures should include forming a metal silicide on the formed crystal layer.
The metal silicide is formed by first forming a covering layer on the formed crystal layer and then forming a metal layer on the covering layer. The metal ions in the metal layer can diffuse into the covering layer to form the metal silicide.
However, semiconductor devices made by such current technologies tend to cause short-circuit among different devices in the formed semiconductor structure, leading to malfunction of the semiconductor devices. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems.